A solar cell is a device that converts solar energy directly into electricity by the photovoltaic effect. In silicon solar cells, the material absorbs solar irradiation by generation of charge carriers that are transported out of the cell and into an external electrical circuit. In order to force the charge carriers out of the cell, a p-n diode needs to be built in to the device. This is usually done by diffusion of boron and phosphorus into the silicon wafer. The current extraction is done at metal to semiconductor interface areas, where the silicon is connected to the external circuit. The contacts to the different polarity regions need to be physically separated in order to prevent electrical shunting. Back-contact back-junction (BC-BJ) silicon solar cells comprise silicon solar cells where the complete metallization and the diffused regions are located on the backside of the cell. This solar cell concept has shown high energy conversion efficiencies because of the eliminated front surface shading compared to conventional front contacted silicon solar cells. The production of BC-BJ silicon solar cells is, however, more challenging, more expensive, and less mature than that of conventional silicon solar cells. The challenges are mostly related to the alignment and structuring of the closely spaced diffused regions on the back of the cell. Originally this type of cell design was processed with the use of 4-6 photolithography masking steps, which is regarded incompatible with large-scale production of cost competitive solar cells. More recently, BC-BJ silicon solar cell concepts that are based on lower cost processing techniques have been developed, but still there is a need to further reduce the cost of solar cell production to make it a cost competitive source of electricity.